London Mayor Sadiq Khan has warned that a potentially “devastating” cut in government funding for the Metropolitan Police could force him to cut frontline officer numbers.

The Met has a strategic ambition, originally set by former Mayor Boris Johnson, to maintain officer numbers at or around 32,000 but Mr Khan says the need to slash costs in the wake of government funding cuts could force him to abandon the target.

During the last Mayoral term the frontline was maintained despite funding cuts of more than £600m, a feat achieved by slashing management layers, sacking thousands of PCSOs and civilian staff, closing police stations and vacating the Met’s world famous Scotland Yard HQ in Victoria.

Now police leaders and the Mayor’s Office for Policing and Crime, which oversees the Met, are being asked to absorb a further £400m in cuts imposed by central government.

To achieve this, the force is working to further reduce back office costs and reconfigure how some services are delivered, including trialling a move away from dedicated Borough command structures to a new cluster approach where multiple boroughs’ manpower and resources are pooled.

Despite these efficiencies, the Met faces a funding gap which Mr Khan says risks him having to sanction reductions to the frontline.

The Mayor, who today published a new Police and Crime plan setting out the Met’s priorities for the next four years, has raised an additional £27m for policing via his share of the council tax.

Mr Khan has also committed the force to allocate an additional dedicated officer to each ward, a move which will help boost the Met’s visibility and provide reassurance to local communities.

However he warns that a pending review into police funding and the government’s refusal to fill the £170m gap between the cost of the Met’s national policing duties – including providing diplomatic protection, policing protests and ensuring the security of overseas dignitaries – and the funding it receives for this work means he cannot guarantee to maintain the current frontline officer strength.

Launching his plan during a visit to South London, Mr Khan said: “Crime is rising again, our population is booming, and our already tight budgets are in danger of further, potentially devastating Government cuts.

“As we deliver this strategy over the coming years, I will continue to fight tooth and nail to protect our vital police services and make sure they have the funding they need to keep us safe now and in the future.”

Craig Mackey, the Met’s acting Commissioner, said that to meet the “major” funding cuts being imposed, the force would have to “change the way it recruits, operates, and evolves.”

He added: “We have an ambitious transformation programme which is already underway and that will deliver a 21st century police service for London, strengthening local policing, making us more diverse, more efficient, and in short – the best police service possible for the next four years.”